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Photoshop Tips
Photoshop Fundamentals: Three Simple Photo Manipulations
By Big Al Gruswitz
Dateline: June 5, 2005
Version: Photoshop 7
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| Just by applying basic filters, you have the power to add photographic grain or a realistic cast shadow
in seconds, and you can command moiré to disappear just as quickly.
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(a) Click to enlarge
(b)
(c)
(d)
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Moiré Nomoiré
You see a photo in a sample book and
want to put it into a layout, but after
scanning it, you get a moiré pattern
due to the image’s screen dot pattern
(a). How do you get rid of it so it looks
decent? There are a several methods you
can use, none of which are perfect. You
can rescan using the scanner’s descreening
option, which will help, but here’s a
quick way to bypass rescanning:
- Choose Filters > Noise > Dust &
Scratches. Depending on the image,
a 1- or 2-pixel Radius with Threshold
set to 0 will dither the image enough
to blend the screen pattern. Go too
far, and the image will look out of
focus. You’ll notice the filter also gets
rid of most of the dust that was on the
scanning bed. In my prescription ad
photo, I used a 1-pixel Radius (b).
- If a 1-pixel Radius looks too screened
and 2-pixel Radius looks too blurry
(c), Cancel the filter and access the
Channels palette. Turn off the visibility
of the Black channel, and apply the
filter again to further dither the Cyan,
Magenta, and Yellow channels while
retaining the sharpness of the Black
channel (d).
Remember, any printed material you
scan has a copyright! You cannot
reproduce any image scanned from
published works without permission.
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(a)
(b)
(c)
(d)
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Real-life Shadows
Shadows made in Photoshop tend to
look off—a real-world shadow does not
contain a solid color with an evenly out-of-
focus edge. Due to ambient light, a
shadow is softer at the edges and lighter
farther from the object. Try this trick
for more realistic shadows for elements
against a solid color background:
- Make your Background layer a new
layer (double-click it), choose Select >
Color Range, click in the background
area of the preview, and click OK.
- Option/Alt-click the Add a mask icon
at the bottom of the Layers palette to
create a silhouette. Command/Ctrl-click
the mask thumbnail, double-click
the Edit in Quick Mask Mode icon in the
toolbox, and choose Selected Areas.
- Choose Edit > Transform > Distort, and
position the mask in the perspective
you want for a shadow (a). Although
the shadow appears above the element,
it’s only a selection at this point.
- Choose Filter > Blur > Gaussian Blur to
soften the mask’s edges, and press Q
to return to Standard Mode.
- Add a new layer beneath, and fill it
with 100% black (b). Don’t use a four color
black or you’ll get banding. If
your background is not white, set the
layer blending mode to Multiply.
- Press Q, select the Gradient tool, and
choose the Foreground to Transparent
option. Draw a gradient masking the
shadow more in the back than in the
front (c).
- Return to Standard Mode, and apply
a Gaussian Blur to soften the shadow.
With the selection still active, Option/
Alt-click the Add a mask icon and the
shadow gradually fades (d). Add a
solid-color layer at the bottom of the
stack. Now that’s realistic!
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(a) Click to enlarge
(b)
(c)
(d)
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Grain Preservation
When you airbrush or clone areas of
a grainy photo (a), you may end up
smoothing them until they stand out
from the grain. In my example, I cloned
the left side of the photo, and you can
see the difference in grain (b). In the
old days of airbrush retouching, the
retoucher would lightly spatter paint
on an area to match the grain. You can
do it better in Photoshop:
- Add a new layer, select the clone
stamp tool, and check Use All Layers
in the Options bar.
- After retouching, zoom into the area
that needs more grain, and choose
Filter > Noise > Add Noise. Typically,
setting the Amount between 4–6%
is effective, depending on the image’s
graininess (c).
- Choose Filter > Blur > Blur to soften
the noise just enough to make it look
like clumpy photographic grain (d).
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Big Al Gruswitz has been art director
and associate creative director with
agencies such as Campbell Ewald and
Saatchi & Saatchi. He runs Boundless
Creativity, which specializes in complex
retouching and realistic illustrations.
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